[rb2013]

The original version of the NM24 used the 20 bit PCM63P and was based on the LITE DAC50 (you can still buy the boards on Ebay).
 
It looks like the NM24 is in it's second iteration using the LITE DAC60 board with the true 24 bit PCM1704K's.
 
Old version: http://www.ti.com/product/pcm63

 
http://www.dagogo.com/monarchy-audio-m24-dac-preamplifier-sm-70-pro-solid-state-monoblock-amplifiers-review
 

 

I found that I liked having the options offered by the M24. Although I used the SS DAC function very little in comparison to the Tube DAC, I can see where the comparison can be extremely compelling. One can become familiarized with the SS DAC to the point that any tube compliment change will be easily compared. This is the first unit that I have ever seen which allows such direct, fixed comparison to a standard. Sure, one can swap cables and units to compare a SS to Tube DAC, but not on the fly! If you really want to know if a particular set of tubes measures better in your mind, the SS function gives you a yardstick to measure.

 
Now upgrading from the supplied Sovtek 6n23p (6dj8) will improve the sound by a large degree.  See my review/shootout of the 6922(6n23p, 6dj8, ECC88, E88CC, CCa, E188CC, etc...).

http://www.head-fi.org/t/761078/6922-tube-review-17-top-6922-6n23p-e88cc-cca-7308-e188cc-tubes
 
With the very best tubes the sound is world class - my favorites are the 'Holy Grail' '75 Reflektor Silver Shield Single Wire Getter Posts.  A few folks who tried these and the '74 version call them 'Magic Tubes'!

.  An easy drop in replacement.

 

[Wildcatsare1]

He has moved to the PCM1704K's, offered to upgrade my DAC chips as well, but I stuck with the 63P, wanted to learn their sound first. He no longer "piggy backs" them.

Any opinions on the sonics of the 63 versus the 1704?

 

[rb2013]

He has moved to the PCM1704K's, offered to upgrade my DAC chips as well, but I stuck with the 63P, wanted to learn their sound first. He no longer "piggy backs" them.

Any opinions on the sonics of the 63 versus the 1704?

Never heard the PCM63 - but many have said it's better then the 1704.  I don't know about that - why would he change other then couldn't find the 63's anymore.  You used to be able to find lot's of LITE DAC50's around super cheap - not anymore.  Been looking to one for awhile.  LITE is not making them anymore - but the DAC60 is easily available.  And even stock (no mods) and upgraded tubes is a killer DAC for the money.  But it won't do naive DSD and doesn't have a i2s input for DxD files.
 
But how many folks have truly recorded and mastered DSD or DxD (352K/24bit) music files.  Anyway I use the DSD to PCM converter in Foobar for the few naive DSD files I have (not PCM to DSD conversions) - works great .  And the SoX up/down sampler - upsample my 16/44K redbook wav files to 96K.
 
EDIT BTW see the Gustard U12 and Melodious MX-U8 threads for a great discussion on excellent sota USB DDC interfaces.  I'm using the MX-U8's togreat effect and will try a Hydra Z soon.

 

[Wildcatsare1]

Bob, one of my next purchases will be the MX-U8, I appreciate your advice!

 

[rb2013]

Bob, one of my next purchases will be the MX-U8, I appreciate your advice!

Thanks!  I just ordered one of these - Breeze Audio to compare to my lightly modded Gustard U12 and MX-U8s.
 
Hoping this is the best - low price - $152.  Very nice design.
http://www.ebay.com/itm/271948361421?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 
The Hydra Z with a linear ps may be the true sota  - but at $1000 is very expensive.

 

[Wildcatsare1]

Thanks!  I just ordered one of these - Breeze Audio to compare to my lightly modded Gustard U12 and MX-U8s.

Hoping this is the best - low price - $152.  Very nice design.
http://www.ebay.com/itm/271948361421?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

The Hydra Z with a linear ps may be the true sota  - but at $1000 is very expensive.

Looking forward to hearing how the Breeze compares to the Melodious. Noob question, what is the IIs connection? Is the AES/EBU a good connection as well?

 

[rb2013]

Looking forward to hearing how the Breeze compares to the Melodious. Noob question, what is the IIs connection? Is the AES/EBU a good connection as well?

i2s is another high bandwidth connection, originally designed for internal use in cd players between the transport and the dac sections.  There lacks a clear pinout standard to compatibility is a nightmare.  AES/EBU is very similar to SPDIF coax, but better, with a much stronger signal.  It was designed for very long cable runs.
 
Although sometimes criticized - good old SPDIF Coax RCA works just great for me.

 

[evillamer]

He has moved to the PCM1704K's, offered to upgrade my DAC chips as well, but I stuck with the 63P, wanted to learn their sound first. He no longer "piggy backs" them.

Any opinions on the sonics of the 63 versus the 1704?

 
Many dac designers including Mike Moffat(Schiit Audio), Ken Ishiwata(Marantz) prefer the sound of PCM63P over PCM1704UK. Ken Ishiwata mentioned in a video on whathifi(youtube) that the newer silicon production process(CMOS) used in PCM1704 cannot deliver the same high current output as the older DACs.

 

[Wildcatsare1]

Can PCM63 K chips be stacked for higher resolution?

 

[evillamer]

Can PCM63 K chips be stacked for higher resolution?

I think you can sum up multiple dacs to increase output accuracy(reduced distortion) but the PCM63P is limited by it's supported input data which is 20bits. But who cares anyway right? Most of music out in the world are 16bit PCM 44.1/48KHz.

 

[vlach]

Sweet unit!  Built around a Lite DAC 60 as well.  Using the 24 bit PCM1704K.  Looks like he adds another board for volume control and pre-amp section.
He stays mostly with the stock caps (but using decent, but not great red box Wima's in place of the blue box Rifa's - for couplers).  He also replaces the R-Core with toroidal transformers - this is curious to me - as R-Cores are known to be much better at electrical noise filtering then toroidal.  Toroidal better at delivering dynamic current - which in a DAC not as important (like an amp).  He possibly does this for the added current needed in the pre-amp.

Here was my Lite DAC60 before extensive mods:




I have a really well designed (and sounding) integrated that uses both.  R-core for the Pre-amp stage and dual large torodials for the power stage:




He also changes the circuit to allow using it as a pre-amp as well I believe.  Has the true (not a just a tube buffered opamp) tube output stage.

Very interesting, I had no idea the Monarchy Audio DACs were based on the Lite DACs, even the casings look very similar and the display looks exactly the same on both.

 

[rb2013]

   
Many dac designers including Mike Moffat(Schiit Audio), Ken Ishiwata(Marantz) prefer the sound of PCM63P over PCM1704UK. Ken Ishiwata mentioned in a video on whathifi(youtube) that the newer silicon production process(CMOS) used in PCM1704 cannot deliver the same high current output as the older DACs.

Funny the very best designers swear by the NOS 16 bit Philips TDA1541A - like Audio Note, Zanden, AMR. etc...
 
All these implemented in a slightly different way.  The best version of these are the double crown S2 chips. They are super scarce and command top dollar.
http://www.ebay.com/itm/1-x-Dual-16-bit-DAC-IC-PHILIPS-DIP-28-TDA1541AS2-TDA1541A-S2-twin-Crown-DIP-28-/171770479207?hash=item27fe518267
 

 
It's like a cult following of these vintage R2R chips.
http://www.dutchaudioclassics.nl/philips_tda1541-s2/
http://www.dutchaudioclassics.nl/Overview-Philips-TDA1541-based-cdplayers/
http://www.adventuresinhifiaudio.com/28/06/2010/is-the-tda-1541-dac-still-relevant-today-the-amr-cd-77-compared/
 
The $15,000 Zanden 5000 Mk.IV/Signature D/A converter

Model 5000 Mk.IV/Signature 16-bit D/A converter
The Model 5000 Mk.IV/Signature was designed to achieve "Linear full bandwidth phase," something the Zanden literature claims is an area where all other digitally filtered DACs fall short. Do they? Does the Zanden achieve it? Zanden's approach is to use its own, patented analog filter, which the company claims has the best phase characteristics of any filter on the market. The 5000 Mk.IV doesn't include digital brick-wall filtering or, as I've already pointed out, any oversampling or upsampling. This DAC is strictly premium "old school" (ca 1985): Philips' TDA-1541A "double crown," which Zanden feels is "the best sounding chip ever made," and which hasn't been made since the late 1990s. The output is tube-driven via a single 6922 using Zanden's patented single-stage, zero-feedback circuit. Needless to say, Zanden claims to use the highest-quality parts and construction throughout.​

Like the 2000P transport, the 5000S DAC is a two-box design. The chassis base and the rear and front panels are made of 16mm-thick aluminum, while the curving cover of polished stainless steel causes headshakes of admiration from competitors and lust from my friends.​

A tube-rectified power supply using one 6X4 and two 6CA4 tubes provides an unbridgeable vacuum gap that is said to block noise from entering the system—the same rationale Brinkmann uses for its vacuum-tubed motor drive. The power supply, housed in yet another case of exquisitely mirrored stainless steel, is meant to be displayed, not hidden away on a bottom shelf, as I was forced to do.​

Three front-mounted knobs control On/Off, absolute polarity, and input choice. The rear panel features I²S, AES/EBU, BNC, and RCA S/PDIF inputs, analog outs, and a multipin power-supply jack. And that's what $15,470 buys you.​

http://www.stereophile.com/cdplayers/1106zanden/#qEgXdAiMTOb3IreM.97

 

[rb2013]

Can PCM63 K chips be stacked for higher resolution?

Yes - my APL DAC uses 8 32-bit AKM DACs per channel.  According to Alex running in serial lowers the distortion - but it does not increase the resolution.  The PCM63's doubled up or tripled up would still be 20 bit.
 
See Kingwa's implementation of mulitple PCM1704's in his ref Audio-gd Ref DAC 7.1 (using 8 1704UK DAC chips) and Ref DAC 10.2 (4 1704UK's)
 
http://www.tonepublications.com/macro/audio-gd-reference-10-2-dac-and-more/

 

[evillamer]

According to Ti Engineers, summing up dacs can increase bit resolution(1bit or 2bits).
 

might be able to combine two 16-bit DACs open loop and maybe achieve 17 or 18 bits of accuracy but I think it would be very challenging to push the boundary up to 24 bits without adding an ADC (something capable of 24 bit accuracy) etc. to "close to loop" and provide feedback. 

 
http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/304238/1068238

 

[rb2013]

  According to Ti Engineers, summing up dacs can increase bit resolution(1bit or 2bits).
 
 
http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/304238/1068238

So would that mean the Audio-gd was 28 bits?  I don't think so.  If true the APL NWO with 20 DAC's per side would be 52 bits (they use 32 bit AKM DAC chips)
http://www.6moons.com/audioreviews/aplhifi/nwo30go.html